usb: phy-generic: Use gpiod_set_value_cansleep

The nop_reset and shutdown methods are called in a context that can sleep,
so use gpiod_set_value_cansleep instead of gpiod_set_value.

If you've connected the reset line to a GPIO expander, you'd get a kernel
"slowpath" warning with gpiod_set_value.

Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>